Question: Global using support for `CSharpCompilationOptions`

Could we use the global usings feature when compiling source code?

It seemed the CSharpCompilationOptions.WithUsings method would not work as expected.

Sample code:

var code = @"
public record Post
{
    public int Id { get; set; }
    public string Title { get; set; }
    public string Description { get; set; }
    public DateTime UpdatedAt { get; set; }
}
";
var syntaxTree = CSharpSyntaxTree.ParseText(sourceText, new CSharpParseOptions(LanguageVersion.Latest));
var references = new[]
        {
            typeof(object).Assembly,
            Assembly.Load("netstandard"),
            Assembly.Load("System.Runtime"),
        }
        .Select(assembly => assembly.Location)
        .Distinct()
        .Select(l => MetadataReference.CreateFromFile(l))
        .Cast<MetadataReference>()
        .ToArray();
var assemblyName = $"DbTool.DynamicGenerated.{GuidId.NewGuid()}";
var compilation = CSharpCompilation.Create(assemblyName)
    .WithOptions(
        new CSharpCompilationOptions(OutputKind.DynamicallyLinkedLibrary)
        // support only for script? https://stackoverflow.com/questions/38795447/roslyn-effect-of-csharpcompileroptions-withusings
        .WithUsings(new[]
        {
        "System",
        "System.Collections.Generic",
        "System.IO",
        "System.Linq",
        "System.Net.Http",
        "System.Threading",
        "System.Threading.Tasks"
        })
    )
    .AddReferences(references)
    .AddSyntaxTrees(syntaxTree);
using var ms = new MemoryStream();
var compilationResult = compilation.Emit(ms);

I would get an error as follows:

The type or namespace name ‘DateTime’ could not be found (are you missing a using directive or an assembly reference?)

[CyrusNajmabadi]

That property is for csx usings. However as you are not compiling csx files, but instead are compiling cs files, it’s not the right option. The semantics if C’s and csx are not the same. Thanks!

[StefH]

@WeihanLi A possible workaround would be to add these to the code:

// <auto-generated/>
global using global::System;
global using global::System.Collections.Generic;
global using global::System.IO;
global using global::System.Linq;
global using global::System.Net.Http;
global using global::System.Threading;
global using global::System.Threading.Tasks;

More info here : https://stackoverflow.com/questions/72904348/roslyn-csharpcompilation-with-global-implicit-usings